This invention relates to a numerical control information generating system which receives data denoting the shape of a work upon completion of a machining process and the shape of the work prior to the machining process, and which generates numerical control information associated with the machining process based on such data.
FIG. 1 is a block diagram of a prior art numerical control information generating system including a data input section 2, which receives data from an external data input unit 1 and outputs input data SA, and an input data separating section 3 which receives the input data SA from the data input section 2 separates at each machining step the input data SA into before-machining shape data SB, after-machining shape data SD and tool data SF and respectively outputs at each machining step thus separated data to a before-machining shape storing section 4 for the before-machining shape data SB, an after-machining shape storing section 7 for the after-machining shape data SD and a step tool data storing section 10 for the tool data SF. That is, the before-machining shape storing section 4 receives and stores the before-machining shape data SB from the input data separating section 3, the after-machining shape storing section 7 receives and stores the after-machining shape data SD, and the step tool data storing section 10 receives and stores the step tool data SF. The numerical control information generating system further includes a before-machining shape dividing section 5 which divides for each machining step the machining areas of the work according to the before-machining shape data SB and forms resultant before-step-machining shape data SC; a before-step-machining shape storing section 6 which stores the before-step-machining shape data SC formed by the before-machining shape dividing section 5; an after-machining shape dividing section 8 which divides for each machining step the machining areas of the work according to the after-machining shape data SD and forms resultant after-step-machining shape data SE; an after-step-machining shape storing section 9 which stores the after-step-machining shape data SE formed by the after-machining shape dividing section 8; a display data selecting section 11 which receives the before-machining data SB, the before-step-machining shape data SC, the after machining shape data SD, the after-step-machining shape data SE and the step tool data SF, selects data to be displayed at a display unit 13 such as CRT and outputs the same as the display data SG; a display data output section 12 which receives the data SG and outputs the same as a display signal SH to display unit 13; a numerical control information generating section 14 which receives the before-step-machining shape data SC, after-step-machining shape data SE and the step tool data SF and generates numerical control information SI; and a numerical control information output section 15 which receives thus generated numerical control information SI and externally outputs the same in the form of a paper tape 16, a magnetic disc 17 or communication signals 18.
The prior art numerical control information generating system generates the numerical control information, which has machining cycle reference points for each machining step, so that a tool is first moved from the position where the tool is changed or from the machining cycle reference point of a preceding machining step to the machining cycle reference point of the machining step where the work is to be machined, the machining cycle is executed in series and upon completion of the machining cycle, the tool is positioned at the machining cycle reference point.
FIG. 2 illustrates the above-mentioned process, in which the tool is first moved from a position PT where the tool is changed to a reference point P70, executes a series of the machining cycle on a work W1, returns from an end point P71 of the machining cycle to the reference point P70, and then moves to the position PT. FIG. 3 shows another example wherein the tool first takes the path "1" from the point PT to the first cycle reference point P80, executes the first series of the machining cycle on a work W2, and returns from the point P81 to the point P80 along the path "2". The tool takes the path "3" from the point P80 to the reference point P83 for the second machining cycle, executes the second series of the machining cycle on the work W2, returns via the path "4" from the end point P82 to the reference point P83 and then to the position PT along the path "5".
In the above-mentioned prior art numerical control information generating system, substantial time is expended in moving the tool when the same tool is used for plural steps, from one machining cycle reference point to another. More particularly, the system must return the tool at the particular reference point set for each step everytime a step ends, and to move the tool to the reference point of the subsequent step along a path where the tool does not interfere with the work. Moreover, when the tool is being moved from the tool change point to the cycle reference point or from the reference point to the tool change point, the tool is likely to interfere with the work depending on the positional relation between the work shape upon completion and the machining step.